In general, a battery package is used in electric or hybrid-electric vehicles. A battery package includes several battery modules, disposed at regular intervals in a holder, and electrically and physically connected with each other.
The temperature of the battery modules increases during use. The modules are therefore cooled to prevent degradation of performance. In addition, since the battery modules do not smoothly operate at very low temperatures, such as in the winter, there is a need to heat them.
A fan is typically provided at either one or both sides of the battery package, and is used both for cooling and heating. However, the battery modules located nearest the fan are easily cooled or heated, whereas those located farther downstream are only slightly cooled or heated, because they exchange heat with the air that has already exchanged heat with those upstream.